THE record number of spoilt votes at last month's Scottish elections were largely caused by major faults in the design of the ballot paper, according to an academic study.

Researchers at Strathclyde University have concluded that thousands of people made mistakes because they did not understand the instructions on the papers which, for the first time, asked them to mark two votes on a single sheet.

In both Glasgow and Edinburgh, some of the instructions were truncated to make room for the 23 different parties on the regional list. This, the researchers concluded, was a key reason why people got confused and spoiled their papers.

The findings, by Dr Christopher Carman and Professor James Mitchell, concluded that there were a total of 146,097 spoiled papers. This compares to just 15,107 in the 2003 election. Of Scotland's 73 constituencies, there were 16 where the winning margin was less than the number of ballots spoiled.

The elections saw votes counted by electronic machines for the first time. Both the Holyrood votes - the constituency and regional vote - were then placed on the same sheet of A4 paper, unlike in 1999 and 2003, where they were on different sheets.

In regions such as Glasgow and Edinburgh, where there were more parties standing for election, the long list meant that names had to be squeezed in. The researchers concluded this was a key factor in the chaos.

Mitchell said: "There does seem ample evidence that the ballot design was the problem. The relationship between the number of parties on the list and the number of rejected ballots was significant."

Their report concludes: "It will come as no surprise to people familiar with election administration and ballot design that altering a ballot and, more specifically, altering the instructions to voters on the ballot would cause problems in election returns and ballot spoilage."

Ron Gould, a former assistant chief electoral officer of Canada, is currently undertaking an official inquiry into the fiasco on behalf of the Scotland Office.

A spokesman for the Scotland Office said: "The inquiry is under way and we will let it run its course."